Contactless communication objects, such as, for example, contactless communicating integrated circuit cards are used in a very diverse way, for example for making a payment, achieving an identification of the bearer of the contactless communication object or storing information. Cards of this type are, for example, used for controlling access or for automatic payment in the subway. The user simply passes his/her card in proximity to a terminal, for example controlling access to the subway, in order to activate the card which communicates to the terminal the required information for certifying the validity of a season ticket. By using an integrated circuit card which communicates without any contact with a terminal or a port or a contactless reader, the user may, for example, save a lot of time.
In this type of communication system between a terminal or a contactless reader and a contactless communication object, the communication is achieved by emission of radiofrequency waves. The ISO/IEC 14443 standard, established by the International Standardization Organization and the International Electrotechnical Commission, for example defines a set of rules relating to identification cards, contactless integrated circuit cards and proximity cards. According to this standard, the terminal or contactless reader emits radiofrequency signals in a determined spectrum of frequencies around 13.56 MHz, in order to transmit information to the contactless card and energy for powering it. Other features of this standard, for example, relate to anti-collision rules when a terminal or contactless reader communicates with several cards simultaneously.
However, applications achieved by contactless communication objects are not generally secured. Indeed, contactless communication objects, such as for example cards, are generally enabled automatically upon their passing in an area within range of a terminal or contactless reader, the range area corresponding to a region of space around the terminal or reader, in which the radiofrequency signal emitted by the terminal or reader has sufficient power for enabling the contactless communication object. Thus, the bearer of a contactless communication payment card may be taxed, without any valid reason, accidentally or by a hacker terminal or reader. A technical problem of the cards or contactless communication objects is therefore to protect these cards or these objects against possible intrusions or against involuntary use.
Further, a contactless communication object such as for example a card, may generally be used by any user. With a stolen subway access card, it is for example possible to open paying access gates. Another technical problem of the cards or contactless communication objects is therefore to allow their use by a user or a determined group of users, in order to, for example, protect these cards or these objects against theft.
Patent application WO 2005/031663 teaches about a payment device relating to contactless payment cards, secured by measuring a biometric parameter of the user. A reader of the biometric parameter thus communicates with the payment card in order to authorize enabling of the card and to make a payment, the card by default being, for example, in a disabled state. However, the making of such a secured payment device requires modification of the layout of the electronic circuit of the contactless payment card in order to have a secured communications link between the biometric reader and the payment card on the one hand, and a communications link with a controlled payment terminal in an enabled or disabled state on the other hand. These complex changes brought into a payment card, the volume of which is very limited, are therefore very costly. Moreover, such a security device requires having a biometric reader associated with each payment card.
A scrambler is also known from document WO 2005/052846, for scrambling the contactless reading of data media by a reader emitting electromagnetic sweep signals, having a radio interface for receiving electromagnetic signals, having analysis means for analyzing the electromagnetic signals received by the radio interface, and having scrambling signal generator means for generating a scrambling signal, the analysis means for analyzing the received electromagnetic signals being provided in order to identify the sweep signals of the reader from the received electromagnetic signals, and when the sweep signals are detected, in order to transmit a control signal to the scrambling signal generator means, the scrambling signal generator means being arranged in order to generate the scrambling signal and to transmit it via the radio interface upon receiving a control signal. But this type of device does not allow validation or invalidation of the scrambling by the scrambler via controlled switching means, according to the result of a comparison performed by comparison means between a piece of information stemming from interactive authentication means on the one hand and a piece of information stored in the memory storage means on the other hand.